This invention relates to improvements in making shoes and, more particularly, to a method and apparatus for determining the coordinates of a foot, and then making a custom shoe having a shape that depends upon the determined coordinates.
A substantial fraction of the population has a problem obtaining shoes that fit properly and comfortably. Unfortunately, custom-made shoes are presently out of economic reach for most people. Also, inaccuracies in obtaining foot measurements can result in custom-made shoes that are still unsatisfactory.
Various techniques have been proposed in the past for obtaining foot measurements using mechanical means, and then fabricating a custom shoe last from the measurements. For example, in the U.S. Pat. No. 3,696,456 there is disclosed a foot contour measuring device that employs a multiplicity of plastic-tipped "needle-like probes" which are attached to pistons. The probes are urged against the foot, and a variable capacitor is attached to each probe so that the degree of extension of each probe can be determined. Information describing the positions of the probes is converted to produce "foot model data" which is coupled, along with "style model data", to a "last information computer". The information in the computer is utilized, in turn, to control an automatic machine tool for cutting a wooden last on which the custom shoe can be made.
Another mechanical-type of system is disclosed in U.S. Pat. No. 4,454,618, which describes a system and method for forming a custom-made resilient insert for a shoe, based on the contour of the undersurface of a foot.
There are inherent limitations in a mechanical measuring device. First of all, in any contact-type measurement, there is a possibility that the measuring means will disturb the contour it is attempting to measure. Other problems involve possible discomfort to the subject, and long-term unreliability of mechanical components, particularly when a large number of components (such as individual probes) are involved. Further, if the measuring device is relatively complex, with many moving parts (as in U.S. Pat. No. 3,696,456, described above), the equipment will tend to be expensive.
Non-contact measurements using optical techniques have been employed in the prior art for various applications, including measurement of the human body and/or movements of the human body or portions thereof. As examples, reference can be made to the following U.S. Pat. Nos. 4,406,544, 4,575,805, 4,569,358, and 4,600,016. Other prior art patents which deal with measurement of dimensions and with foot analysis are U.S. Pat. Nos. 4,227,813, and 4,534,365.
To Applicant's knowledge, no practical non-contact technique for foot measurement has come into commercial practise. Among the reasons for the absence of such a commercial system or technique is the relative difficulty of obtaining measurements of the foot with accuracy and without undue expense. The two sides of a foot are quite different in contour, and an interrogating medium must achieve appropriate measurements over a substantial portion of the foot surface. The measurements must be made in reasonable time in order to be practical, and the measuring system cannot be unduly complex or expensive.
It is among the objects of the present invention to provide a non-contact method and apparatus for achieving accurate foot measurements without undue complexity, so that custom shoes can be made more readily available to the public at large.